Down-hole drill



April 9, 1963 H. v. sEARs DOWN-HOLE DRILL 2 Sheets-$11651. 1

Original Filed Feb. 8, 1961 INVENTOR HOWARD V. SEARS FIG.

FIG.

ATTORNEYS April 9, 1963 H. v. SEARS 3,084,673 L DOWN-HOLE DRILL v Original Filed Feb. 8, 1961 2 Sheets-Sheet 2 VIII,

INVENTOR HOWARD VISEARS P50 HG. d BYQJMMPMQL FIG' B ATTORNEYS United States Patent lilice Blil Patented Apr. 9, 19u-53 3,684,673 DUWN-HGLE DillrLlL Howard V. Sears, Flat River, Mo., assigner to St. .loseph Lead Company, New York, NX., a corporation of New York Continuation of application Ser. No. 87,879, Feb. 8, 1962i. rhis application Apr. 16, 1962, Ser. No. 1%,45 i9 Claims. (Cl. 121-48) This invention relates generally to improvements in a down-hole drill and more particularly to improvements in a pressure huid-operated drill of the percussion type adapted to enter the hole being drilled so that the percussive forces of the drill are transmitted directly to the drill bit.

It is a major objective of the present invention to provide an advantageous system for directing and controlling the iiow of pressure fluid through the drill so that the hammer operates more efficiently and so that all of the exhaust air is discharged at the bit for more efiicient operation.

An important object is achieved by providing a centrally located tube of circular cross section along which the hammer reciprocates in a chamber provided in the drill housing, the tube serving to convey high -pressure hammer-return air through a rst passage to the chamber near the bottom of the hammer as well as to convey all exhaust air centrally through a separate second passage communicating with the chamber above the place of communication of the iirst passage with the chamber, out through the bit tappet and bit for discharge to the atmosphere.

The central tube eliminates the necessity for double cylinders that provide a duct between them for conducting high pressure hammer-return air anound the inner cylinder to the bottom end of the air cylinder, as is required in heretofore conventional drills of this type.

Another important object is realized in that the central tube enables the construction of smaller diameter drills capable of drilling smaller diameter holes than that possible with drills having the double casing mentioned above.

Still another important objective is realized in that the central air tube eliminates the necessity for a small diameter section on the bottom of the hammer and a mating reduced diameter sleeve which provide an air tight compression chamber for reducing the shock of hammer impact on the forward threaded connection between the cylinder housing and the bit-retaining device when the bit is not in contact with the rock at the bottom of the hole,

Other important advantages are realized in that the central air tube thereby allows the hammer striking face to occupy the entire area between the central air tube and the cylinder housing. Moreover, because the hammer is of symmetrical construction, the hammer can be turned end for end when one striking face begins to wear out so as to secure twice the normal use from this part.

Yet another important object is achieved in that the large impact face areas of the yhammer and bit tappet allow a greater working volume of air to be used to operate the drill at higher speed and heavier impacts, thereby resulting in faster drilling ratesl Another important objective is to provide a drill in which the entire volume of air used in producing useful work is utilized in sweeping drill cuttings from the bottoni of the hole out to the surface. This results in a greater efhciency of operation than when high pressure air must be by-passed to the bit around the work cycle, without doing any useful work, in order to sweep the drill cuttings adequately from the bottom of the hole. Moreover, because the entire volume of air is exhausted into centrally located ports in the center tube high in the machine, and thence through the bit tappet and bit, the cooling elect of expanding air will prevent overheating of the tappet and bit from impact of the hammer.

lOther important advantages and functional results are obtained because the drill design permits installation of a check valve at the bottom of the drill adapted to close the central air passage automatically when the air is turned oft' the machine. The check valve makes it possible to drill in rock formation containing mud and water because its specific location and operation .prevents entry of mud and rock cuttings into any part of the machine through air passages when the air is turned olf.

Another important object is achieved by the use of a single unported cylindrical housing to contain the automatic valve parts, the hammer and the bit tappet. Because the interior wear is concentrated in this one housing part which is also subjected principally to erosion on the outside by drill cuttings as they are blown out of the hole, replacement of a worn cylindrical housing will renew the strength and worn outside diameter of the machine as well as renew the internal lits of the working parts.

By construction the interconnection of the bit tappet with the lower end of the machine, the bit tappet is allowed to drop down from normal operating position when the bit is not in contact with the rock, thereby allowing the hammer to drop down to where an internal groove on the hammer spans both pressure and exhaust ports in the central tube so that the debris is blown from the hole with full pressure and volume of air.

An important object is to provide a down-hole drill that is simple and durable in construction7 economical to manufacture, efficient in operation, and which is fully automatic.

The foregoing and numerous other objects and advantages of the invention will more clearly appear from the following detailed description of a preferred embodiment, and several modilications thereof, particularly when considered in connection with the accompanying drawings, in which:

lF'IG. 1 is a longitudinal cross sectional view of the down-hole drill, illustrating the bit tappet and hammer in its initial position prior to its return stroke;

FIG. 2 is a longitudinal cross sectional view similar to FIG. l, but illustrating the hammer at the end of its return stroke and at the beginning of its power stroke;

FIG. 3 is a fragmentary longitudinal cross sectional view similar to FIG. l, but illustrating the bit and bit tappet fully extended so that said hammer is in full blowing position;

FIG. 4 is a fragmentary perspective view of the center tube utilized in FIG. l;

FlG. 5 is a fragmentary perspective View, partially in cross section, of a modification of the center tube;

lFIG. 6 is a fragmentary perspective View, partly cutaway and in cross section, of a modification of the center tube;

llFIG. 7 is a fragmentary perspective view, partially cutaway and in cross section, of another modiiication of the center tube;

FIG. 8 is an enlarged cross sectional View of the check valve utilized in FIG. l and capable of use with the center tubes illustrated in FIGS. 4, 6 and 7; and

FIG. 9 is a cross sectional View of a modified check valve capable of use with the center tube show-n in FIG. 5.

Referring now by characters of reference to the drawings, and first to FIGS. l and 2, it is seen that the drill unit includes a cylindrical tubular housing generally indicated at 1t). An intermediate housing portion 11 is threadedly connected at its upper end to a top housing portion 12, and is threadedly connected at its lower end to a bottom housing portion 13 constituting a chuck. The top housing portion 12 is adapted to be connected by internal fastening means 14 to a source of iiuid under pressure.

The intermediate housing portion 11 provides a chamber 15 delined at its top end by valve means 16 and at its bottom end by bit tappet 19 constituting a bit-supporting 11183113.

The valve means 16 includes a rst plate Ztl seating on a shoulder provided by the top rim of intermediate housing portion 11. Formed in first plate 2t) are a plurality of valve passages 2i communicating with the top end of chamber 15. A second plate 22 seats on top of the lirst piate 2d and is provided with a plurality of valve passages 23 that are aligned and communicate with valve passages 21 formed in rst plate 20.

Disposed between the top of second plate 22 and a shoulder formed on the top housing portion 12 is a closure cap Z4, the cap 24 providing an internal compartment 25.

A tubular valve member 26 is reciprocally mounted within the second plate 22, the interior of valve member 26 communicating with the compartment 25 of closure cap 24. The valve member 25 includes a peripheral ange 27 that seats on second plate 2?. in its lowered position to close the valve passages 23, and opens the cap compartment 25 to a plurality of valve passages 3i) formed in the closure cap Z-/i communicating with the source of pressure fluid. ln its uppermost position, the flange 27 of Valve member 25 closes the cap compartment 25 by sealingly engaging the cap 24, yet opening the valve passages 39 to the aligned valve passages 23 and 21.

The bit tappet 17 is reciprocally mounted within the lower housing portion 13. Specifically, Ithe bit tappet 17 is splined to the lower housing portion 13 so that it is drivingly rotated by the cylindrical housing 1li, and is reciprocally movable within limits.

Attached to the lower end of bit tappet 17 is a suit` able drill bit 31. rl`he drill bit 31 engages the bottom end of housing 15 to determine the fully retracted position of bit tappet 17. The head of the bit tappet t7 engages the spline on the lower housing portion 13 to `determine its fully extended position as is shown in FIG. 3.

The bit tappet 17 is provided with an internal bore 32 that communicates at its bottom end with passages 33 formed in drill bit 31. For reasons which will later appear, the tappet bore 32 and the bit passages 33 are hereinafter designated a discharge passage.

Extending longitudinally in chamber 15 is a center tube 34 (FlG. l), the upper end of which is secured by the rst valve plate Zit of the valve means, and the lower end of which is slidably mounted within the bore 32 of bit tappet 1.7.

A. hammer 35 is provided with a longitudinal bore adapted to receive the center tube 34 in substantial sealing relation, the hammer 35 being reciprocal in chamber 15 between the valve means 16 and bit tappe't 17. For reasons which will later appear, the hammer 35 is provided with an internal groove 36 that spaces an intermediate porti-on of the hammer 35 from the center tube 34.

The center tube 34 is provided with an internal partition 37 that divides the tube 34 into two separate passages 4@ and 41. As is best seen in FiGS. l and 4, the first passage dit communicates with the interior of valve member 26 at the upper end of center tube 34 and communicates with the bottom of chamber 15 through iirst tube port 42. When the bit tappet 17 is fully raised as is shown in FiG. l, the tube port 42 communicates with the chamber 15 below hammer 35.

The center tube 3d is provided with a second and a third tube ports 43 and 44 above the first tube port d2, these tube ports 43 and 44 communicate the second passage 41 with the chamber 15. The second passage 41 also communicates with the Itappet bore 32 through the lower end of center tube 34.

A check valve d5 (FIG. l) is secured to the lower end of center tube 34 and is located within the second passage A51, the check valve being adapted to assure ilow through the second passage 41 only in one direction. The details of construction of check Valve $5 are clearly sho'wn in FIG. 8.

From PEG. 8 it is seen that the check valve 45 includes a cylindrical casing 46 that seats on an internal ring 4'7 iixed to the bottom end of tube 34. The ring 47 is provided with a center openinU 5l? communicating the lower end of casing 43 with `the tappet bore 32. The top of casing dei is closed by plug 51. Reciprocally mounted within casing 46 is a tubular check valve member 52 shown in a lowered and in a raised position in FIG. 8. The interior of tubular check valve SZ communicates with the opening 5@ at the bottom of the center tube. The casing 46 is provided with a plurality of valve ports 53 that are adapted to be opened and closed by reciprocating check valve member 52.

The check valve member 52 is provided with a pressure surface 5d that communicates with the second passage d1 through the valve ports 53. Furthermore, the check valve member 52 is provided with a pressure surface 55 that communicates with the bottom opening 5t) through the interior or check valve member 52.

When fluid pressure is exerted through the second passage 41, such pressure raises the check valve member 52 to open the valve ports 53, and thereby places the second passage 41 in direct communication with the tappet bore 32. On the other hand, when liuid pressure is turned olf, the pressure differential on pressure surfaces 54 and 55 causes the check valve member 52 to drop and close the valve ports 53. The pressure existing at the bottom of the machine in the drill hole, acts on pressure surface 55 through the tubular check valve member 52 to maintain the check valve member in its closed position until the fluid pressure is subsequently turned on.

It will be assumed that the initial starting position of the component elements of the drill are shown in FIG. l. When lluid pressure is turned on through the top of the cylindrical housing 10, the fluid is directed through valve passages 30 into the cap compartment 25 and thence through the tubular valve member 26 into the first passage `441. This uid pressure is directed from the lirst passage `40 through the first tube port 42 against the lower face of hammer 35, thereby lifting the hammer 35 for a return stroke.

As the hammer 35 is raised in this return stroke, 4fluid in the chamber 15 labove the hammer 35 is moved through third tube port 44 into the second passage 41, and consequently fed through the bit discharge passage. The hammer will first clear the second tube port 43, thereby placing the tube ports 42 and `43 in direct communication. The high pressure iiuid will then flow directly from the rst passage 40, through tube port 42, into second tube port `43 and thence into the second passage 41 where it is directed out the bottom of the machine through bit discharge passage. The momentum of hammer 35 will then carry it past the third tube port 44 so as to close such tube port 44. The air in the upper part of chamber 15 is then compressed by hammer 35 and acts through valve passages 2,1 and 23 to raise the valve member 26 to the position illustrated in FIG. 2.

The machine is now conditioned for a power stroke. The pressure lluid is directed from valve passages 3@ into the aligned valve passages 2,3 and 21 and is then directed into the top of chamber 15 above hammer 35. This high pressure drives the hammer 35 downwardly with force. As the hammer moves downwardly, the lluid below the hammer is moved through the second tube port 43, into the second passage 41 and out the bottom of the machine. The hammer 35 will first clear the third tube port 44. The high pressure fluid will then be directed from the upper portion of the chamber through the third tube port 44 directly into the second passage 41 and then directed through the -bit 31. The hammer 35 continues in its power stroke to strike the bit tappet 17 so as to extend the bit 31 from housing 10.

When the second tube port 43 is closed by the hammer 35 as the hammer descends, the' fluid below the hammer in the chamber '15 is compressed through the first tube port 42 and into the first passage 46. This increase in fiuid pressure in the first passage 40 acts on valve member 26 to lower the valve member 26 to its initial position shown in FIG, 1. After the bit tappet 17 and the drill bit 31 have been extended upon impact by the hammer 35, the weight of the unit will cause the cylindrical housing 1) to move downwardly so that the bit tappet is again fully retracted. The mechanism is now conditioned for another cycle of operation.

If, for any reason, the bit tappet 17 and attached drill bit 31 fall free as a result of there being an absence of supporting formation, the hammer 35 will drop to the position illustrated in FIG. 3 on top of the bit tappet 17. In this position, the internal groove 36 of hammer 35 places the first tube port 42 in direct communication with the second tube port 43. Consequently there is a continuous blowing action of pressure fluid from the first passage 4f), into the second passage `41 and out the bottom of the machine through the tappet bore 32 and bit ports 33. The machine is subsequently conditioned automatically for cycling operation when the bit 31 engages the bottom of the drill hole and the bit tappet 17 is fully retracted as is shown in FIG. 1.

Of course, it will be readily apparent that the center tube 34 can be of different constructions to provide the same results. For example, the tube 34 in FIG. 6 includes an inner tubular portion 56 that provides a first passage 57 communicating the valve means 16 with a first tube port 66 that corresponds to the first tube port 42 previously described with respect to FIGS. 1 and 4. An outer tube portion 61 is spaced from the inner tube portion 56 to provide a `separate second passage 62. It will be seen from FIG. 6 that an intermediate length of the inner tubular portion 56 is reduced so that the second passage communicates with chamber as determined by the reciprocating action of hammer 35. The second passage 62 places the chamber 15 in direct communication with the open bottom end of the outer tubular portion 61.

A check valve of the ltype fully disclosed in FIG. 8 can be attached to the bottom of this center tube 34 (FIG. 6) in the same manner as was utilized with respect to the center tube 34 (FIG. 4).

Briefiy described, fiuid pressure through the first passage 57 .and out the first tube port 60 below the hammer 35, thereby acting to raise the hammer for its return stroke. As the ham-mer 35 is raised, the fluid in chamber 15 above the hammer flows between the hammer and the tube into the second passage 62. First, the hammer 35 will clear the top of outer tubular portion 61 so as to place the first tube port 60 in direct communication with the second passage 62 through the reduced intermediate tube length. Upon continued movement upwardly of hammer 35, the hammer 35 engages the enlarged upper portion of the tube 34 to close oii the second passage 62 with the chamber 15 above the hammer, thereby conditioning the valve means 16 for a power stroke .as previously described.

As the hammer 35 is moved downwardly in a power stroke, the fiuid in chamber 15 below the hammer moves along the reduced intermediate tube portion and into the second passage 62. The hammer 35 will first clear the reduced tube portion so that the high pressure iiuid above the hammer fiows between the hammer and reduced tube portion and thence flows into the second passage 62. Continued movement of hammer 35 in its power stroke closes off the reduced tubular portion with the chamber 15 below the hammer so that the fiuid is compressed through the first tube port 66 and in the first passage 57 to actuate the valve means 16, and thereby condition the machine for another return stroke.

Another center tube construction is illustrated in FIG.

is introduced initially' 7. In this modification, the center tube 34 includes an inner tubular portion 63 that is open at the top to communicate with the tubular valve member 26 and is open through a first tube port 64 to the lower end of chamber 15 below hammer 35. Again, it will be noted that the first tube port 64 corresponds to the first tube por-t 42 previously described in the center tube of FIG. 4. The inner tubular portion 63 provides a first passage 65.

An outer tubular portion 66 is spaced from inner tubular portion 63 to provide a separate second passage 67 that is open at the bottom of center tube 34. The outer tubular portion 66 is provided with a second tube port 70 communicating the second passage 67 with the chamber 15 above the first tube port 64. A third tube port communicates the second passage 67 with the chamber 15 above the second tube port 76. It will be noted that the second and thi-rd tube ports 70 and 71 correspond respectively to the second and third tube ports 43 an-d 44 previously described with respect to the center tube in FIGS. l and 4.

The operation and functional advantages of the center tube 34 illustrated in FIG. 7 is the same as that previously described with respect to the center tube 34 of FIG. 4.

Again, the check valve 45 shown in FIG. 8 may be advantageously utilized and mounted in the bottom end of the center tube 34 illustrated in FIG. 7.

Still another center tube construction is shown in FIG. 5 In the embodiment of FIG. 5, the center tube 34 includes Ian inner tubular portion 72 having fiattened sides. The inner tubular portion 72 provides a first passage 73 that communicates at its top end with the tubular valve member 26, and which communicates with the lower end of chamber 15 through a first tube port 74 as will be eX- plained later.

A11 outer tubular portion 75 surrounds the inner tubular portion 72 and is spaced from the fiat sides to provide a second passage 76. The out-er tubular portion 75 is provided with a reduced section 77 below the first tube port 74. The outer tubular portion 75 is provided with ia second tube port 3f) that communicated the second passage 76 with the upper end of chamber 15 above the first tube port 74.

A check valve 81, the details of which are illustrated in FIG. 9, is attached `to the bottom of center tube 34 illustrated in FIG. 5. From FIG. 9 it is `seen that the lower end of the center tube 34 of FIG. 5 is closed by a plug 82. Reciprocally mounted about the end of the tube 34 is a check v-alve member 83 that is movable between limits as determined by abutment with the reduced tube portion 77 and by abutment with a ring S4 `attache-d to closure plug 82. Upon reciprocation, the check valve member 83y is adapted to open or close a plurality of cheek valve ports 85 formed .in the lower end of the center tube. The second passage 76 communicates with the tappet bore 32 through the check valve port 85 when the check valve member 31 is raised upon exertion of fluid pressure through the second passage 76.

When the bit tappet 17 is fully retracted Within housing 10 and the hammer 35 seats on the top of the bit tappet 17, the internal groove 36 of hammer 35 ybridges the first tube port 74 and the reduced tube portion 77 so that pressure fluid is directed into the first passage 73, out through the first tube port 74, `and subsequently -along the internal hammer groove 36 and down the reduced tubular portion 75 to the bottom face of hammer 35. The hammer is then raised ina return stroke.

As the hammer 35 is raised in its return stroke, the fiuid in the upper end of the chamber is moved through the second tube port 36 into the second passage 76. The eX- istence of fiuid pressure in the second passage 76 raises the check valve member 83 to open the check valve ports 85, thereby placing the second passage '76 in direct communication with the discharge passage so that the fiuid is ejected through the drill bit 31.

In this return stroke of hammer 35, the internal hammer groove 36 iirst bridges the first tube port 7d and second tube port Si? to place the first and second passages 73 and 76 in direct communicationso that high pressure fluid Hows directly out the bottom of the machine. Then, the hammer 35 closes the second tube port 8o Aand compresses the fluid at the top of the chamber so as to condition the valve member 26 for a power stroke as previously described.

During the power stroke, the iiuid under pressure throws the hammer downwardly. As the hammer moves` Vdownwardly, the iiuid at the bottom end of the chamber iiows upwardly along the reduced tubular portion 77 and along the internal hammer groove 35, into the second tube port Si), and consequently is moved ythrough the second passage 76 and out through the drill bit. Then, upon continued movement of the hammer in the power stroke, the hammer 35 opens the second tube port $9 so that the high pressure fiuid is moved directly therethrough into the second passage 76. The hammer then strikes the bit tappet i7 and extends the drill brit 31.

In this embodiment of FIG. 5, when the bit tappet 17 land drill bit 31 drop free upon the absence of any supporting Iformation below the drill bit, the hammer 35 will fall suiiciently with the bit tappet i7 so that the iirst tube port 74' is opened above the hammer 35. This action places the first tube port 74 in direct communication with the superjacent second tube port Si) .so that there is a continuous iiow or blowing of iuid under high pressure through the first and .second passages and consequently out the bottom of the machine.

Although the invention has lbeen described by making detailed refer-ence to a single preferred embodiment and several modifications of a part thereof, such detail is to be understood in an instructive, rat-her than in any restrictive sense, many variants being possible within the scope of the claims hereunto appended.

This application is `a continuation of my application Serial No. 87,879 tiled February 8, 1961, now abandoned.

I claim as my invention:

l. A down-hole drill, comprising a housing adapted for connection at one end to a source of fluid pressure, an annular hammer reciprocally mounted within said housing, valve means ,adjacent said one end of the housing, a `bitsupporting means reciprocally mounted at the other end of the housing, a tube supported within said housing `and extending through the hammer bore, the tube having one end in pressure iiuid transmitting communication with said bitsupporting means, port means in said valve for directing pressure iiuid alternately to one end of the ham-mer and into the other end of said tube, hammer controlled port means adjacent said one end ofthe tube for directing pressure iiuid .to the other end of the hammer and further valve means `for selectively directing pressure iuid from said tube Ito sai-d bit-supporting means.

2. In a down-hole drill, a tubular housing adapted for connection at its top end to .a source of iiuid pressure, a chamber within said housing, a reciprocal hammer within `said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciproca-lly mounted at the bottom end of 'the chamber, a drill bit attached to said bit-supporting means, a tube supported )at its top end by said valve means and extending through the hammer bore in substantial sealing lrelation, the tube having its bottom end received in said bit-supporting means, said tube including a first passage communicating the valve means with said chamber below said hammer when the bit-supporting means is raised, land a second passage communicating with said chamber above the place of communication of said rst passage with said chamber, said hammer opening and closing said second passage upon reciprocation, said hammer opening said `second passage below the hammer when the hammer is partly iraised and closing said second passage above the hammer when the hammer :approaches its fully raised position in said chamber, the bit-supporting means and the bit being provided with a-discharige passage communicating with said second passage, the valve means being adapted selectively to direct pressure fluid to the chamber above said hammer or to direct pressure iiuid through said iirst passage.

3. In a `down-hole drill, a tubular housing adapted for `connection at its top end to `a source of `fluid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an 'axial bore therethrough, vaive means including a reciprocal valve member supported at the top end of said chamber, a bitsupporting means reciprocally mounted at 'the bottom end of the chamber, a drill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending 'through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including a first passage communicating the valve means with said chamber below said hammer when the bit-supporting means is raised, and a separate second passage communicating with said chamber above the place of communication of said first passage with said chamber, said hammer opening and closing `said second passage relative to said chamber upon recipnocation, the bit-supporting mean-s and said bit being provided with la discharge passage communicating with said second passage, said valve member in one position directing fluid pressure through said first passage to lift the hammer for a return stroke, said second passage being open above said hammer :as the hammer is initially lifted but said hammer maintaining said second passage closed below said hammer, said hammer opening the .second passage below the hammer during .the return stroke and -said hammer closing the second passage above the hammer as the hammer approaches the end of its return stroke, the valve member disposed in another position to direct pressure fluid Ito the chamber above said hammer to lower the hammer in a power stnoke, said second passage being `open below Said hammer as lthe hammer is initially lowered in Asaid power stroke but said hammer closing said second passage above said hammer, said hammer opening said lsecond passage above said hammer during the power stroke and closing the second passage below the hammer as the hammer approaches the end of its power stroke.

4. In a down-holedrill, a tubular housing adapted for connection at its top end to -a source of iiuid pressure, a chamber with said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top of said chamber, said valve means including a reciprocal valve member supported at the top of said chamber, said valve member being tubular, and a closure cap `overlying the top of said tubular valve member, a bit-supporting means reciprocal-ly mounted at the bottom of said chamber, a drill bit attached to said bit-supporting means, a tube supported `at its top end by said valve means and extending 4through the hammer bore in substantial sealing relation,

the tube having its bottom end received in said bit-supporting means, said tube including a first passage communieating the interior of said 'tubular valve member with said chamber below said hammer, and ya second passage communicating with the chamber above the place of communication of the first passage with said chamber, the bit-supporting means and bit being provided witha discharge passage communicating with said second passage, the valve member in one position directing fluid pressure through the valve member and into said first passage, and in another position directing :fluid pressure around the valve member and into the chamber 'above said hammer.

5. The combination and arrangement of elements as recited above in claim 4, but further characterized in that said hammer opens and closes said second passage upon reciprocation, said hammer opening said second passage below the hammer when vthe hammer is partly r-aised and closing said ysecond passage 'above the hammer when the hammer approaches its fully raised position in said chamber t-o actuate ysaid valve member.

6. In a down-hole drill, a tubular housing adapted for connection lat its top end 'to la source of fluid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, ra tube supported at its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including an inner tubular portion defining a first passage communicating the v-alve means with said chamber below said hammer when the bit-supporting means is raised, and said tube and inner tubular portion defining a separate second passage communicating with said chamber above 'the place of communication of said first passage with said chamber, said hammer opening and closing said second passage upon reciprocation, the bit-supporting means and the bit being provided with a discharge passage communicating with said second passage, the valve mean-s being adapted selectively to direct pressure lluid through .said first passage to li-t the hammer in a return stroke, or to direct pressure fluid to the chamber above said hammer to lower the hammer in la power stroke, said hammer opening said second passage below the hammer and subsequently closing the second passage -above the hammer during the return stroke, and said hammer opening the second passage above the hammer and subsequently closing the second passage below the hammer during the power stroke.

7. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of fluid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, a tube supported at'its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including a first passage communicating the valve means with said chamber below said hammer, and a second passage communicating with the chamber above the place of communication of the first passage with said chamber, and a check valve disposed in said second passage at the bottom end of said tube, said check valve being adapted to close said second passage automatically when the fluid pressure is turned oil so as to preclude entry of mud and cuttings into said second passage and chamber, the bitsupporting means and the bit being provided with a discharge passage communicating with said second passage through said check valve, the valve means being adapted selectively to direct pressure fluid to the chamber above said hammer or to direct pressure fluid through said first passage.

8. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of fluid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means including a reciprocal valve member supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including a first passage communicating the valve means with said chamber below said hammer when the bit-supporting means is raised, and a second passage communicating with the chamber above the place of communication of said first passage with said chamber, said hammer opening and closing said second passage upon reciprocation, the valve member disposed in one position to direct pressure fluid through said first passage to lift the hammer in a return stroke, said hammer closing said second passage above the hammer during the return stroke, and the valve means in said other position directing fluid pressure to the chamber above the hammer to lower the hammer in a power stroke, said hammer opening the said second passage during the power stroke, the bit-supporting means and bit being provided with a discharge passage communicating with the second passage at the bottom of said tube.

9. The combination and arrangement of elements as recited above in claim 8, but further characterized by the provision of a check valve in the said second passage at the bottom end of said tube, said check valve being adapted to close said second passage automatically when fluid pressure is turned off so as to preclude entry of mud and cuttings into said second passage and chamber.

l0. ln a down-hole drill, a tubular housing adapted for connection at its top end to a source of fluid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means including a reciprocal valve member supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the hammer bore in a substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including a first passage communicating the valve means with said chamber below said hammer when the bit-supporting means is raised, and a separate second passage communicating with said chamber above the pl-ace of communication of said rst passage with said chamber, said hammer opening and closing said second passage upon reciprocation, said hammer opening said second passage below the hammer when the hammer is partly raised and closing said second passage above the hammer when the hammer approaches its fully raised position in said chamber, and a check valve disposed in said second passage at the bottom end of said tube, said check valve being adapted to close said second passage automatically when fluid pressure is turned ofr", said bit-supporting means and bit being provided with a discharge passage communicating with said second passage through said check valve, said valve member being disposed in one position to direct pressure fluid to the chamber above said hammer and in another position to direct pressure fluid through said first passage.

l1. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of fluid pressure, a

chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said hammer having an internal groove about said tube, said tube including a first passage communicating the valve means with said chamber below said hammer when the bit-supporting means is raised, and -a separate second passage communicating with said chamber above the place of communication of said first passage with said chamber, the bit-supporting means and the bit being provided with a discharge passage communicating with said second passage at the bottom of said tube, the valve means being adapted selectively to direct pressure fluid to the chamber above said hammer or to direct pressure fluid through said first passage, said first and second passages being 1 1. placed in direct communication by said internal hammer groove as the hammer is lowered when the bit-supporting means and attached bit drop freely, whereby to cause a continuous blowing through the tube passages and said discharge passage.

12. The combination and arrangement of elements as recited above in claim 11, but further characterized by the provision of a check valve in said second passage at the bottom end of said tube, said check valve being adapted to close said second passage automatically when tluid pressure is turned ott so as to preclude entry of foreign material into said second passage and chamber.

13. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of iluid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit'attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the hammer bore `in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said hammer having an internal groove about said tube, said tube including a rst passage communicating the valve means with said -chamber below said hammer when the bit-supporting means is raised, and a separate second passage communicating with said chamber above the place of communication of said rst passage with said'chamber, said hammer opening said second passage below the hammer when the hammer is partly raised and closing said second passage above the hammer when the hammer approaches its fully raised position in said chamber, the bit-supporting means and bit being provided with a discharge passage communicating with said second passage at the bottom end of said tube, the valve means being adapted to direct pressure iluid to the chamber above said hammer or to direct pressure fluid through said tirst passage, said iii-st and second passages being placed in direct communication by said internal hammer groove as the hammer is lowered when the bit-supporting means and attached bit drop freely7 whereby to cause a continuous blowing through the tube passages and said discharge passage.

14. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of uid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, a -tube supported at its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including an inner tubular portion open at the top to provide a iirst passage communicating with the valve means, said tube being provided with a iirst port communicating the rst passage with said chamber below said hammer when the bit-supporting means is raised, the :tube and said inner tubular portion being spaced to provide a separate second passage communicating with said ychamber above said iirst port, said hammer opening and closing said second passage upon reciprocation, said hammer opening said second passage below the hammer when the hammer is partly raised and closing said second passage above the hammer when lthe hammer approaches its fully raised position in said chamber, the bit-supporting means and the bit being provided with a discharge passage communicating with said second passage at the bottom of said tube, the valve means being adapted selectively to direct pressure iiuid to the chamber above said hammer or to direct pressure fluid through said rst passage.

15. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of Huid pressure, a chamber within said-housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of -thhe chamber, a drill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including -a partition providing a iirst passage communicating with the valve means, said tube being provided with a rst port communicating the iirst passage with said chamber below said hammer when the bit-supporting means is raised, said partition providing a separate second passage, the tube being provided with a second port communicating with said chamber above the said rstport, and being provided with a third port communicating with said chamber above the Said second port, said hammer ope-ning and closing said second and third ports uporrreciprocation, said hammer opening said second port below the hammer when the hammer is partly raised in the return stroke to exhaust pressure fluid through the second passage, and said hammer closing said third port above the hammer when the hammer approaches the top of its return stroke, the bit-supporting means and bit being provided with a discharge passage communicating with said second passage at the bottom end of said tube, valve means being adapted selectively to direct pressure fluid to the chamber above said hammer or to direct pressure fluid through said rst passage.

16. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of huid pressure, a chamber with said housing, a reciprocal hammer with said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, ya bit-supporting means recip-rocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means said tube including means providing a first passage communieating with the valve means, said tube being provided with a rst port communicating lthe rst passage with said chamber` below said hammer when the bit-supporting means is raised, said tube means providing a second separate passage, the tube being provided with a Second port communicating with said chamber above said rst port and being provided with a third por-t communicating with said chamber above said second port, said hammer opening and closing said second and third ports upon reciprocation during a return stroke and a power stroke, the bit-supporting means and bit being provided with a discharge passage communicating with said second passage at the bottom of said tube, the valve means being adapted selectively to direct pressure Huid through said first passage and through said first port to raise said hammer for a return stroke, said hammer opening said second port during the return stroke to exhaust pressure fluid through sai-d second passage and out said bit, and said hammer subsequently `closing said third port during said return stroke so as to actuate said valve means for a power stroke, said valve means being adapted to direct pressure fluid to the chamber above said hammer to lower the hammer in a power stroke, said hammer opening said third port during the power stroke to exhaust pressure nid through said second passage and out said bit, and subsequently closing said second port as the hammer approaches the end of its power stroke to force pressure fluid through said tirst por-t and first passage so as to actuate said valve means for another return stroke of said hammer.

17. In a down-hole drill, a :tubular housing adapted for connection at its top end to a source of uid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a dr-ill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, the tube including a lirst passage communicating the valve means with said chamber below said hammer, and a separate second passage communicating with the chamber above the place of communication of the rst passage with said chamber, a check valve means carried by the lower end of said tube including a valve port communicating with said second passage, a reciprocal check valve member movable to open or close said valve port, said check valve member having one surface subjected to fluid pressure from said second pasage through said valve port and adapted to move the check valve member toward a port-open position upon application of ilu-id pressure, the bit-supporting means and bit being provided with a discharge passage communicating with said second passage through said valve port, said check valve member having another surface subjected to external pressure through said discharge passage tending to move the check valve member toward a port-closed position when the iluid pressure is terminated, the valve means being adapted selectively to direct pressure fluid to the chamber above said hammer or to direct pressure fluid through said first passage.

18. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of fluid pressure, a chamber within said housing, a reciprocal hammer within said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including a first passage communicating the valve means with said chamber below said hammer, and a second separate passage communicating with the chamber above the place of communication of the first passage with said chamber, the valve means being adapted selectively to direct pressure uid to the chamber above said hammer or to direct pressure iluid to said iirst passage, a check valve means carried by the lower end of said tube including a tubular casing w'thin .the lower tube end, said casing having a valve port communicating the second passage with the said lower tube end, and a tubular check valve member reciprocally mounted in said casing and adapted to open or close said valve port, said check valve member placing the casing interior above the valve member in communication with the lower tube end, said check valve member having one surrace subjected to lluid pressure from said second passage through said valve port and adapted to move the check valve member toward a portopen position upon application of tiuid pressure, the bitsupporting means and bit being provided with a discharge passage communicating with said second passage through said :open lower tube end and said check valve port, said check valve member having another surface subjected to external pressure through the open lower tube end and discharge passage tending to move the check valve member toward a portaclosed position when the liuid pressure is terminated.

19. In a down-hole drill, a tubular housing adapted for connection at its top end to a source of fluid pressure, a chamber within said housing, a reciprocal hammer with said chamber, said hammer having an axial bore therethrough, valve means supported at the top end of said chamber, a bit-supporting means reciprocally mounted at the bottom end of the chamber, a drill bit attached to said bit-supporting means, a tube supported at its top end by said valve means and extending through the .hammer bore in substantial sealing relation, the tube having its bottom end received in said bit-supporting means, said tube including a rst passage communicating the valve means with said chamber below said hammer, and a separate second passage communicating With the chamber above the place of communication of the tirst passage with said chamber, the valve means being adapted selectively to direct pressure uid to the chamber above said hammer or to direct pressure -iiuid through said first passage, a check valve means carried by the lower end of said tube including a closure cap attached to the lower end of said tube, the lower `end of said tube being provided with a valve port above said closure cap communicating with said second passage, and -a tubular check valve member rcciprocally mounted on the lower end of said tube and adapted to open or close said valve port, means on said closure cap holding said check valve member on said lower tube end, said check valve member having one surface subjected to fluid pressure from said second passage through said check valve port and adapted to move the check valve port toward a port-open position upon application of fluid pressure, said bit-supporting means and bit being provided with a discharge passage communicating with said second passage through said check valve port, said check valve member having another surface subjected to external pressure through said bit discharge passage tending `to move the check valve member toward a port-closed position when the fluid pressure is terminatedi No references cited. 

1. A DOWN-HOLE DRILL, COMPRISING A HOUSING ADAPTED FOR CONNECTION AT ONE END TO A SOURCE OF FLUID PRESSURE, AN ANNULAR HAMMER RECIPROCALLY MOUNTED WITHIN SAID HOUSING, VALVE MEANS ADJACENT SAID ONE END OF THE HOUSING, A BITSUPPORTING MEANS RECIPROCALLY MOUNTED AT THE OTHER END OF THE HOUSING, A TUBE SUPPORTED WITHIN SAID HOUSING AND EXTENDING THROUGH THE HAMMER BORE, THE TUBE HAVING ONE END IN PRESSURE FLUID TRANSMITTING COMMUNICATION WITH SAID BITSUPPORTING MEANS, PORT MEANS IN SAID VALVE FOR DIRECTING PRESSURE FLUID ALTERNATELY TO ONE END OF THE HAMMER AND INTO THE OTHER END OF SAID TUBE, HAMMER CONTROLLED PORT MEANS ADJACENT SAID ONE END OF THE TUBE FOR DIRECTING PRESSURE FLUID TO THE OTHER END OF THE HAMMER AND FURTHER VALVE MEANS FOR SELECTIVELY DIRECTING PRESSURE FLUID FROM SAID TUBE TO SAID BIT-SUPPORTING MEANS. 